Biowaffe Z-15 was synthesized after the discovery of a bacteria on the surface of Element 115 that was found in Germany during the war.Adolf Hitler and his generals including Heinrich Himmler and even Colonel Klaus Von Adalard of the SS was there.Hitler told Klaus to find a way of making the bacteria a deadly contagion of war and release it upon America.Klaus accepted the terms of his Fuhrer and started to formulate some way of making it deadly.Eventually,Klaus had discovered that diseases such as chickenpox,Smallpox and other contagions were to be used,However he tested them and they came out to be failures,Until one day when one of his soldiers sneezed on his viles accidentally and Klaus ordered the man to report to the infirmary for examination.He got back to work and then realized that the cold cells and germs of the soldier were bonding with the bacteria and so he tested a subject with this and the subject died,Although not completely dead.Klaus realized that the subject had no will power or even ability to wield weapons,Just the need to feast on the flesh of human beings.He realized that the subject was only 75% dead,With the brain and nerve cells still operational and the irresistable hunger for flesh.With these findings,Klaus reported to Hitler and Hitler planned Operation:Valhalla.

Biowaffe Z-15 was designed out of the cold virus and the bacteria from Element 115 that was found by the Nazis during World War 2.The Cold Virus was non living,However the bacteria was able to live through it's travel to Earth and as a result,The bacteria became food for the Cold virus,Making the virus hard to control and soon it became a big part of the insatiable appetite for the subject infected with it.If launched by any kind of missile or rocket,The virus is spread through the air and after 10 seconds the virus was no longer airborne,Now it is transferred by either a scratch or bite,However if anyone infected feeds on a dead human carcass,The carcass can come back to life.If injected into the body,The virus takes 2-4 hours in order to destroy the immune system and as a result the person will feel weak,Then the brain will completely shut down.After 2 minutes,The brain will reactivate and will follow any kind of sound or noise that it hears due to the zombie relying on instinct in order to find flesh to feast on.Vampires can be infected with this virus as well for example Colonel Klaus Von Adalard was a Vampire before he was infected with the contagion by Tony Secord l,However this is different due to the fact that Vampires are dead and the vampire infected still keeps all it's powers however their powers are somewhat decreased in a way.God like beings such as Tony Secord and Lara Croft are completely immune to Biowaffe Z-15 due to their immune systems being too strong to penetrate.The remains of a dead human being can also be resurrected,Even if they've been buried for the last 70 years,So anyone could return from the dead,Either by injection or having the pathogen airborne.The most unique about the resurrected infected are that they are capable of remembering their time of death and their skills range from hand to hand combat-Using Fully Automatic Weaponry.

Infected individuals or "Zombies" are all but invincible.The brain is the main source of life for the zombie and since it powers the nerves,Separating the head from the body or any head trauma such as a bullet to the head will kill them,Once these methods are used on a zombie,They will not come back.